There are a wide variety of bag making machines, and a number of known pouch machines. Pouch machines may have continuous or intermittent motion, and have a generally horizontal or vertical machines film path. In either case a continuous web of material or film is converted into a series of individual pouches. Generally, the continuous film is folded in half over a plow or forming shoulder. The folded web is transported through at least one cross-sealer, which has seal bars in the cross-machine direction, to form cross seals, thus creating a strip of pouches interconnected by transverse seals (and open opposite the fold). A cut-off unit separates the continuous film into individual pouches by cutting each cross-seal. Individual pouches are subsequently filled and sealed at a separate machine.
Prior art intermittent motion pouch machines alternately advance the film, and then the various processing stations process the film when it is stationary (the dwell time). Examples of such pouch machines include. U.S. Pat. Nos. 5,181,365 and 6,195,967 (hereby incorporated by reference).
Pouch machines perform a number of processes in addition to the sealing and cutting described above that form the pouch, such as forming a zipper seal (or weld) on a film, forming a long seal (machine direction) on the film, and applying a “slider” closure on the film. One or more of these processes, along with feeding/folding the film, forming cross-seals, and separating adjacent pouches are performed in succession, and, depending on what process are performed, any of a variety of pouch style may be made.
Typically, the machinery performing the processes are housed in a single structure (called a cab or cabinet). A single controller controls the entire process and all of the needed machinery. The controller is typically housed in a separate structure. Such a pouch machine has one common electrical control cabinet housing the complete electrical requirements for the complete specialized machine line. This makes for an inflexible, limited product range machine, and its expensive to change product styles.
For example, when a pouch manufacturer desires to make a particular style pouch, the machinery needed to perform the required processes is determined, and a specialized machine, including a controller, is built. If the pouch manufacturer desires to make a different style pouch a new machine must be built, or the existing machine must be disassembled, and then rebuilt with the appropriate machinery and controls.
Another type of prior art pouch machine provides for modules which each house machinery for a specific task, rather than a single cab. A single central controller is provided to control each of the various modules. Changing pouch styles requires changing modules, and rewiring of the controller, and possibly a redesign of the controller so that it can control the new modules.
Such prior art machines are not readily modified to produce pouch styles other than those for which the machine was originally built. Accordingly, a pouch machine that can be readily altered to produce different pouch styles is desirable.
Pouch machines are typically 30 or more feet in length due to the great number of processes that have to be done to the web. The film or web is drawn through the machine by a single drawroll assembly. The drawroll is registered to a registration mark on a film. An example of such a prior art machine is found in U.S. Pat. No. RE 35,067, hereby incorporated by reference. Some prior art machines have dual drawroll systems, such as that described in U.S. Pat. No. 5,086,964 (hereby incorporated by reference). Such a system uses one drawroll for registration and the other drawroll for advancing the web and setting web tension between the drawrolls.
Given the length of the machine, it is typical for the registration to be off at some of the processing stations, particularly those a greater distance from the registration sensor. Thus, prior art pouch machines provide that the machinery or tooling that performs the process on the web (cross sealing, punching, die cutting, etc.) are each on an independent carriage that is moved to the position of the stopped web to accurately register the process to the web, film, mark, seal, etc.
Accordingly, a pouch machine that does not require processing devices to be moved along the machine direction for proper registration is desirable.
Pouch machines in the prior art includes web guides. Generally, such guides were developed for use with continuous motion machines and the guides were separate from the rolls drawing or driving the film or web. The web guides were needed because the web often tracked toward one side of the machine or the other. This may be caused by mis-alignment of drawrolls, sections of the machine being out of proper alignment with each other, material which is thicker on one edge of the web than the opposite edge or stretched material. Whatever the cause, it is important to keep the web tracking properly through the machine.
FIG. 3 shows such a prior art web guide system that includes guide roller or rollers 320 moving in a lateral and angular direction. This movement steers the web laterally into the entering span 321 of the drawrolls 309. The guide is mounted on slides or bearings 322, with a point of rotation 323. While this technology may be better than other prior art web guides, it was developed for a moving web, it has several shortcomings when applied to an intermittent machine such as a pouch machine such as locating the nips (from guide rolls 320) in or near the longitudinal sealer section, the web is not guided properly in intermittent motion, and it requires additional framework and additional rack and rail length is required.
Accordingly, a web guide system that uses existing draw rolls is desirable.